Using sound localization to gain depth perception for the visually impaired through sensory substitution
- Authors: De Klerk, James Carmichael
- Date: 2020
- Subjects: People with visual disabilities Directional hearing--Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/50779 , vital:42674
- Description: The visually impaired do not have the visual ability to localize objects in three-dimensional space, rather, they rely on their other senses to gain depth perception. Sensory substitution is the concept of substituting one sense for another, normally substituting an impaired sense with a functioning sense. Visual-to-auditory sensory substitution substitutes an impaired visual sense with a functioning auditory sense. This research aimed to investigate and develop techniques for visualto-auditory sensory substitution – using sound localization as a sensory substitution for depth perception. The research started by investigating the characteristics of human audition with a particular focus on how humans localize sounds. It then looked at existing visual-to-auditory sensory substitution systems and the techniques they used. From the existing systems, a system known as MeloSee was chosen as a baseline for developing and evaluating further sensory substitution prototypes. The baseline prototype (𝑃0) was then implemented and a preliminary study performed. Based on the knowledge gained from the preliminary study, baseline implementation and the background research, a set of improvement recommendations were generated. The next iteration – Prototype 1 (𝑃1) – was then developed based on the recommendations. A comparative study between 𝑃0 and 𝑃1 was then performed. Based on the study, another set of improvement recommendations were generated. From the recommendations, a final prototype was developed – Prototype 2 (𝑃2). The last comparative study was then performed between 𝑃0 and 𝑃2, with a third set of recommendations being generated as a result. From the studies it was found that participants using 𝑃0 were able to identify when they were approaching large objects such as walls. 𝑃1 built on that, improving the ability to identify the quadrant of a nearby isolated object. 𝑃2 built on 𝑃0 and 𝑃1, achieving similar results to 𝑃1 for identifying the quadrant of nearby isolated objects, and improving on 𝑃0 and 𝑃1 with regard to depth discrimination – especially for navigation tasks where there were no obstacles. Based on the three sets of recommendations and what was learnt over the course of the research, a set of visual-to-auditory sensory substitution techniques were presented. The techniques aim to be useful for implementing visual-to-auditory sensory substitution systems, which would provide the visually impaired with the visual ability to localize objects in three-dimensional space through sound.
- Full Text:
- Date Issued: 2020
- Authors: De Klerk, James Carmichael
- Date: 2020
- Subjects: People with visual disabilities Directional hearing--Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/50779 , vital:42674
- Description: The visually impaired do not have the visual ability to localize objects in three-dimensional space, rather, they rely on their other senses to gain depth perception. Sensory substitution is the concept of substituting one sense for another, normally substituting an impaired sense with a functioning sense. Visual-to-auditory sensory substitution substitutes an impaired visual sense with a functioning auditory sense. This research aimed to investigate and develop techniques for visualto-auditory sensory substitution – using sound localization as a sensory substitution for depth perception. The research started by investigating the characteristics of human audition with a particular focus on how humans localize sounds. It then looked at existing visual-to-auditory sensory substitution systems and the techniques they used. From the existing systems, a system known as MeloSee was chosen as a baseline for developing and evaluating further sensory substitution prototypes. The baseline prototype (𝑃0) was then implemented and a preliminary study performed. Based on the knowledge gained from the preliminary study, baseline implementation and the background research, a set of improvement recommendations were generated. The next iteration – Prototype 1 (𝑃1) – was then developed based on the recommendations. A comparative study between 𝑃0 and 𝑃1 was then performed. Based on the study, another set of improvement recommendations were generated. From the recommendations, a final prototype was developed – Prototype 2 (𝑃2). The last comparative study was then performed between 𝑃0 and 𝑃2, with a third set of recommendations being generated as a result. From the studies it was found that participants using 𝑃0 were able to identify when they were approaching large objects such as walls. 𝑃1 built on that, improving the ability to identify the quadrant of a nearby isolated object. 𝑃2 built on 𝑃0 and 𝑃1, achieving similar results to 𝑃1 for identifying the quadrant of nearby isolated objects, and improving on 𝑃0 and 𝑃1 with regard to depth discrimination – especially for navigation tasks where there were no obstacles. Based on the three sets of recommendations and what was learnt over the course of the research, a set of visual-to-auditory sensory substitution techniques were presented. The techniques aim to be useful for implementing visual-to-auditory sensory substitution systems, which would provide the visually impaired with the visual ability to localize objects in three-dimensional space through sound.
- Full Text:
- Date Issued: 2020
A best practice e-learning environment for software training
- Authors: Esterhuyse, Maxine Pier
- Date: 2017
- Subjects: Internet in education Computer-assisted instruction Web-based instruction -- Education
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12165 , vital:27039
- Description: The incorporation of best practice in e-learning environments can increase the probability of success for companies and learners alike. By identifying and understanding the barriers that potential learners may face when interacting with e-learning products, the potential for e-learning failure may be alleviated. There are a variety of benefits that may be realised by companies incorporating e-learning opportunities into their management strategies. However, certain pedagogical principles, metrics and components need to be investigated and implemented in order for a corporate e-learning environment to be successful. The aim of this research is to prototype and evaluate a practical e-learning environment for software training (eLESTP) with e-learning components consisting of interactive learning objects that can guide the development and management of online training in the corporate context. The eLESTP is based on a theoretical contribution that is conceptualised in the form of an e-learning environment for software training (eLESTT). Hence, this study followed a research methodology that is appropriate for educational technologies, namely the Design-Based Research (DBR) methodology, which was applied in iterative cycles. Quantitative and qualitative data was collected by means of a case study, interviews, a focus group and survey. The proposed eLESTP underwent several iterations of feedback and improvement and the result is a real-world solution to the problem at hand. With the purpose of determining the success of corporate e-learning, the barriers and critical success factors for e-learning as well as evaluation criteria were explored. Interviews, a focus group and a survey were conducted in order to validate the investigated literature in a real-world context. Informal interviews enabled a better understanding of the organisational context of this study. The focus group was conducted with customers who were undergoing face-to-face training using conveyancing software developed by Korbitec. Many of the issues faced by learners identified in literature regarding e-learning in developing countries were identified by the participants from the case study. An e-learning survey was used to gather information regarding the intention of Korbitec’s customers to use e-learning as well as their satisfaction with using e-learning. From the survey, it was found that respondents were positive regarding intention to use and satisfaction toward e-learning usage. DBR Cycle 1: Problem Investigation and Proposal entailed the initial problem investigation by conducting a literature review, focus group and survey. DBR Cycle 2: Design Alternative 1 of this study involved a design alternative for eLESTP, namely Prototype 1. DBR Cycle 3: Design and Evaluate Alternative 2 involved the design and prototyping of Prototype 2 for eLESTP as well as the improvement of Prototype 2 through sub-cycles of testing and refinement. The suggestions for improvement were obtained from the relevant stakeholders at Korbitec who are content developers and subject-matter experts. The criteria used to evaluate the success of eLESTP, including its e-learning components, were synthesised and adapted from literature and a new set of evaluation criteria for e-learning environments in software training contexts was proposed. The evaluated eLESTP consists of the technology basis of the Modular Object Oriented Dynamic Learning Environment (Moodle), design guidelines for e-learning components, certification and competency-based training, pedagogical principles and best practice. Overall, eLESTP was positively received by various evaluator groups in formative and summative evaluations. The research results indicate that the use of an e-learning environment for software training purposes was useful and necessary. In support of this Masters dissertation, the following three conference papers have been published and presented at one local conference and two international conferences. In addition, an article has been published in an accredited journal: 1. IDIA 2015, Conference Paper – Zanzibar (Tanzania); 2. Conf-IRM 2016, Conference Paper – Cape Town (South Africa); 3. MCIS 2016, Conference Paper – Cyprus (Europe); and 4. IJIKM 2016, Journal Article.
- Full Text:
- Date Issued: 2017
- Authors: Esterhuyse, Maxine Pier
- Date: 2017
- Subjects: Internet in education Computer-assisted instruction Web-based instruction -- Education
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12165 , vital:27039
- Description: The incorporation of best practice in e-learning environments can increase the probability of success for companies and learners alike. By identifying and understanding the barriers that potential learners may face when interacting with e-learning products, the potential for e-learning failure may be alleviated. There are a variety of benefits that may be realised by companies incorporating e-learning opportunities into their management strategies. However, certain pedagogical principles, metrics and components need to be investigated and implemented in order for a corporate e-learning environment to be successful. The aim of this research is to prototype and evaluate a practical e-learning environment for software training (eLESTP) with e-learning components consisting of interactive learning objects that can guide the development and management of online training in the corporate context. The eLESTP is based on a theoretical contribution that is conceptualised in the form of an e-learning environment for software training (eLESTT). Hence, this study followed a research methodology that is appropriate for educational technologies, namely the Design-Based Research (DBR) methodology, which was applied in iterative cycles. Quantitative and qualitative data was collected by means of a case study, interviews, a focus group and survey. The proposed eLESTP underwent several iterations of feedback and improvement and the result is a real-world solution to the problem at hand. With the purpose of determining the success of corporate e-learning, the barriers and critical success factors for e-learning as well as evaluation criteria were explored. Interviews, a focus group and a survey were conducted in order to validate the investigated literature in a real-world context. Informal interviews enabled a better understanding of the organisational context of this study. The focus group was conducted with customers who were undergoing face-to-face training using conveyancing software developed by Korbitec. Many of the issues faced by learners identified in literature regarding e-learning in developing countries were identified by the participants from the case study. An e-learning survey was used to gather information regarding the intention of Korbitec’s customers to use e-learning as well as their satisfaction with using e-learning. From the survey, it was found that respondents were positive regarding intention to use and satisfaction toward e-learning usage. DBR Cycle 1: Problem Investigation and Proposal entailed the initial problem investigation by conducting a literature review, focus group and survey. DBR Cycle 2: Design Alternative 1 of this study involved a design alternative for eLESTP, namely Prototype 1. DBR Cycle 3: Design and Evaluate Alternative 2 involved the design and prototyping of Prototype 2 for eLESTP as well as the improvement of Prototype 2 through sub-cycles of testing and refinement. The suggestions for improvement were obtained from the relevant stakeholders at Korbitec who are content developers and subject-matter experts. The criteria used to evaluate the success of eLESTP, including its e-learning components, were synthesised and adapted from literature and a new set of evaluation criteria for e-learning environments in software training contexts was proposed. The evaluated eLESTP consists of the technology basis of the Modular Object Oriented Dynamic Learning Environment (Moodle), design guidelines for e-learning components, certification and competency-based training, pedagogical principles and best practice. Overall, eLESTP was positively received by various evaluator groups in formative and summative evaluations. The research results indicate that the use of an e-learning environment for software training purposes was useful and necessary. In support of this Masters dissertation, the following three conference papers have been published and presented at one local conference and two international conferences. In addition, an article has been published in an accredited journal: 1. IDIA 2015, Conference Paper – Zanzibar (Tanzania); 2. Conf-IRM 2016, Conference Paper – Cape Town (South Africa); 3. MCIS 2016, Conference Paper – Cyprus (Europe); and 4. IJIKM 2016, Journal Article.
- Full Text:
- Date Issued: 2017
A comparison of the comfort properties, measured with a sweating manikin (WalterTM), of clothing containing different fibres
- Authors: Britz, Lizaan
- Date: 2017
- Subjects: Textile chemistry Cotton fabrics , Cotton textiles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14752 , vital:27842
- Description: The main objective of the present study was to determine the relative role and importance of worsted suiting fabric fibre blend vis-à-vis fabric structural parameters, on the comfort related properties of 12 clothing ensembles, each comprising a different man’s suit, but the same wool/nylon underwear and cotton shirt. To achieve the objective, the comfort related properties, namely thermal resistance (Rt) and water vapour resistance (Ret) and water vapour permeability index (Im), of the clothing ensembles, as determined by means of WalterTM, a thermal sweating fabric manikin, were subjected to multi-linear and multi-quadratic analysis, as dependent variables, with the various suiting fabric parameters, namely weight, thickness, density, porosity, air permeability and wool content, as independent variables. It was found that the multi-quadratic regression analysis was able to best explain the observed differences in the clothing ensemble comfort related properties, in terms of the differences in suiting fabric properties. The regression analyses were used to isolate and quantify the effects of the various fabric and fibre content variables on the above mentioned comfort related properties of the various clothing ensembles. This study indicated that the suiting fabric structural properties (notably air permeability), had a more significant influence than either fibre blend or suiting fabric, as measured on WalterTM, a thermal sweating fabric manikin.
- Full Text:
- Date Issued: 2017
- Authors: Britz, Lizaan
- Date: 2017
- Subjects: Textile chemistry Cotton fabrics , Cotton textiles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14752 , vital:27842
- Description: The main objective of the present study was to determine the relative role and importance of worsted suiting fabric fibre blend vis-à-vis fabric structural parameters, on the comfort related properties of 12 clothing ensembles, each comprising a different man’s suit, but the same wool/nylon underwear and cotton shirt. To achieve the objective, the comfort related properties, namely thermal resistance (Rt) and water vapour resistance (Ret) and water vapour permeability index (Im), of the clothing ensembles, as determined by means of WalterTM, a thermal sweating fabric manikin, were subjected to multi-linear and multi-quadratic analysis, as dependent variables, with the various suiting fabric parameters, namely weight, thickness, density, porosity, air permeability and wool content, as independent variables. It was found that the multi-quadratic regression analysis was able to best explain the observed differences in the clothing ensemble comfort related properties, in terms of the differences in suiting fabric properties. The regression analyses were used to isolate and quantify the effects of the various fabric and fibre content variables on the above mentioned comfort related properties of the various clothing ensembles. This study indicated that the suiting fabric structural properties (notably air permeability), had a more significant influence than either fibre blend or suiting fabric, as measured on WalterTM, a thermal sweating fabric manikin.
- Full Text:
- Date Issued: 2017
A sedimentological and structural study of the lower Ecca Group, with a focus on facies analysis of the Collingham Formation, north of Grahamstown, SE Karoo Basin, South Africa
- Authors: Slamang, Shereen
- Date: 2017
- Subjects: Formations (Geology) -- South Africa -- Grahamstown Facies (Geology) -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/21099 , vital:29439
- Description: A study of the Collingham Formation was conducted in the area of the Ecca Pass and Committees Drift Road some 20km north of Grahamstown, Eastern Cape. The study incorporates outcrops of the lower Ecca Group, with a focus on the Collingham Formation. The structural and sedimentological characteristics have been documented, and a detailed description and facies outcrop characterization of the Collingham Formation has been undertaken. The combined thickness of the Prince Albert (~55m), Whitehill (~12m), and Collingham (~20m) Formations is approximately 85m. These formations are composed of fine grained parallel laminated mudrocks of mostly silt- and clay-size particles. A general north-easterly dip direction is recorded with three prominent joint directions striking NNE, NNW, and ESE. Intense small scale folding is evident in the Whitehill Formation, and is likely linked to local décollement structures; while north-verging duplex faults in the Prince Albert Formation is possibly linked to a sole thrust/detachment fault rooted in rocks of the Cape Supergroup. The foreland model has been proposed for these deformational structures. Six lithofacies have been recognised in the Collingham Formation, namely; claystone facies, mudstone facies, siltstone facies, chert facies, tuff facies, and shale facies. The Collingham Formation is comprised of an upward fining sequence of sediments; seen from the gradual change from siltstone facies in the lower layers, to mudstone facies, and claystone facies in the upper layers. This was created in a delta environment whereby clay particles were held in suspension in a hypopycnal mouth bar, and slowly settled to form claystone facies. An influx of sediment caused silt particles to settle further out to sea under the influence of gravity in a hyperpycnal mouth bar, thereby forming siltstone facies. Mudstone facies formed as the sediment supply gradually depleted, subsequently reducing the concentration of silt particles. The dominance of clay particles present suggests deposition to have occurred in tranquil waters, in a possible intracratonic basin setting, where the water depth is known to be a lot shallower. An upward decrease in organic content is seen by the colour change of mudrocks from dark grey near the base to dark green grey in the upper layers. Chlorite is commonly found in thin section, SEM, and XRD, and is an indication that the formation was later subject to low grade greenschist facies metamorphism.
- Full Text:
- Date Issued: 2017
- Authors: Slamang, Shereen
- Date: 2017
- Subjects: Formations (Geology) -- South Africa -- Grahamstown Facies (Geology) -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/21099 , vital:29439
- Description: A study of the Collingham Formation was conducted in the area of the Ecca Pass and Committees Drift Road some 20km north of Grahamstown, Eastern Cape. The study incorporates outcrops of the lower Ecca Group, with a focus on the Collingham Formation. The structural and sedimentological characteristics have been documented, and a detailed description and facies outcrop characterization of the Collingham Formation has been undertaken. The combined thickness of the Prince Albert (~55m), Whitehill (~12m), and Collingham (~20m) Formations is approximately 85m. These formations are composed of fine grained parallel laminated mudrocks of mostly silt- and clay-size particles. A general north-easterly dip direction is recorded with three prominent joint directions striking NNE, NNW, and ESE. Intense small scale folding is evident in the Whitehill Formation, and is likely linked to local décollement structures; while north-verging duplex faults in the Prince Albert Formation is possibly linked to a sole thrust/detachment fault rooted in rocks of the Cape Supergroup. The foreland model has been proposed for these deformational structures. Six lithofacies have been recognised in the Collingham Formation, namely; claystone facies, mudstone facies, siltstone facies, chert facies, tuff facies, and shale facies. The Collingham Formation is comprised of an upward fining sequence of sediments; seen from the gradual change from siltstone facies in the lower layers, to mudstone facies, and claystone facies in the upper layers. This was created in a delta environment whereby clay particles were held in suspension in a hypopycnal mouth bar, and slowly settled to form claystone facies. An influx of sediment caused silt particles to settle further out to sea under the influence of gravity in a hyperpycnal mouth bar, thereby forming siltstone facies. Mudstone facies formed as the sediment supply gradually depleted, subsequently reducing the concentration of silt particles. The dominance of clay particles present suggests deposition to have occurred in tranquil waters, in a possible intracratonic basin setting, where the water depth is known to be a lot shallower. An upward decrease in organic content is seen by the colour change of mudrocks from dark grey near the base to dark green grey in the upper layers. Chlorite is commonly found in thin section, SEM, and XRD, and is an indication that the formation was later subject to low grade greenschist facies metamorphism.
- Full Text:
- Date Issued: 2017
A smart home environment to support safety and risk monitoring for the elderly living independently
- Authors: Chiridza, Tongai
- Date: 2017
- Subjects: Multisensor data fusion , Raspberry Pi (Computer) -- Programming Adaptive computing systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14851 , vital:27880
- Description: The elderly prefer to live independently despite vulnerability to age-related challenges. Constant monitoring is required in cases where the elderly are living alone. The home environment can be a dangerous environment for the elderly living independently due to adverse events that can occur at any time. The potential risks for the elderly living independently can be categorised as injury in the home, home environmental risks and inactivity due to unconsciousness. The main research objective was to develop a Smart Home Environment (SHE) that can support risk and safety monitoring for the elderly living independently. An unobtrusive and low cost SHE solution that uses a Raspberry Pi 3 model B, a Microsoft Kinect Sensor and an Aeotec 4-in-1 Multisensor was implemented. The Aeotec Multisensor was used to measure temperature, motion, lighting, and humidity in the home. Data from the multisensor was collected using OpenHAB as the Smart Home Operating System. The information was processed using the Raspberry Pi 3 and push notifications were sent when risk situations were detected. An experimental evaluation was conducted to determine the accuracy with which the prototype SHE detected abnormal events. Evaluation scripts were each evaluated five times. The results show that the prototype has an average accuracy, sensitivity and specificity of 94%, 96.92% and 88.93% respectively. The sensitivity shows that the chance of the prototype missing a risk situation is 3.08%, and the specificity shows that the chance of incorrectly classifying a non-risk situation is 11.07%. The prototype does not require any interaction on the part of the elderly. Relatives and caregivers can remotely monitor the elderly person living independently via the mobile application or a web portal. The total cost of the equipment used was below R3000.
- Full Text:
- Date Issued: 2017
- Authors: Chiridza, Tongai
- Date: 2017
- Subjects: Multisensor data fusion , Raspberry Pi (Computer) -- Programming Adaptive computing systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14851 , vital:27880
- Description: The elderly prefer to live independently despite vulnerability to age-related challenges. Constant monitoring is required in cases where the elderly are living alone. The home environment can be a dangerous environment for the elderly living independently due to adverse events that can occur at any time. The potential risks for the elderly living independently can be categorised as injury in the home, home environmental risks and inactivity due to unconsciousness. The main research objective was to develop a Smart Home Environment (SHE) that can support risk and safety monitoring for the elderly living independently. An unobtrusive and low cost SHE solution that uses a Raspberry Pi 3 model B, a Microsoft Kinect Sensor and an Aeotec 4-in-1 Multisensor was implemented. The Aeotec Multisensor was used to measure temperature, motion, lighting, and humidity in the home. Data from the multisensor was collected using OpenHAB as the Smart Home Operating System. The information was processed using the Raspberry Pi 3 and push notifications were sent when risk situations were detected. An experimental evaluation was conducted to determine the accuracy with which the prototype SHE detected abnormal events. Evaluation scripts were each evaluated five times. The results show that the prototype has an average accuracy, sensitivity and specificity of 94%, 96.92% and 88.93% respectively. The sensitivity shows that the chance of the prototype missing a risk situation is 3.08%, and the specificity shows that the chance of incorrectly classifying a non-risk situation is 11.07%. The prototype does not require any interaction on the part of the elderly. Relatives and caregivers can remotely monitor the elderly person living independently via the mobile application or a web portal. The total cost of the equipment used was below R3000.
- Full Text:
- Date Issued: 2017
Adjusting lion diet estimates to assess lion impacts on small prey in Addo Elephant National Park
- Authors: Gerber, Amarein Judith
- Date: 2017
- Subjects: Wildlife conservation -- South Africa -- Addo Elephant National Park , Lion -- Behavior -- South Africa -- Addo Elephant National Park Lion -- Conservation -- South Africa -- Addo Elephant National Park
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14311 , vital:27542
- Description: Populations of small prey species (< 92 kg) can be regulated by competition, habitat-mediated responses, climate change, disease and predation. Populations of small prey species have declined in the Addo Elephant National Park Main Camp Section since the reintroduction of apex predators (lion and spotted hyaena). One possible explanation is predation by lion and spotted hyaena. However, small prey species are not generally considered preferred prey items of these predators, hence their contribution to predator diets needs to be explored. Global Positioning System (GPS) cluster analysis has emerged as a viable approach to locate lion kills for lion diet estimation in AENP, however this technique is known to bias diet estimates to large prey species. Understanding the impact of lion predation on populations of small prey in Main Camp therefore requires better estimates of lion diets. This study investigated the potential underestimation of small prey species in lion diet estimates by combining the data from scat analysis and carcasses located at GPS clusters. The adjusted lion diets were then used to investigate if the impact of lion predation could explain declines in small prey, by relating lion prey preferences to prey population trends in Nyathi. Using the results from Nyathi, it could then be inferred whether lions could have been responsible for the declines observed in Main Camp. Six GPS-collared lions provided location data used to construct individual movement paths, along which spatio-temporal clusters of GPS locations (n = 4896) were identified for ground investigation. Carcasses (n = 643) were recorded at the GPS clusters and scats (n = 256) were collected at GPS clusters with or without carcasses. Data from the located carcasses and scat collections were then used to create a history of feeding events for each collared lion in Main Camp-Colchester and Nyathi from a) carcasses alone or b) a combination of scats and carcasses, based on an estimated short and long lion throughout period. Relative prey availability was estimated based on camera trapping in Nyathi in high lion, low lion and no lion use areas, as lions may encounter some prey species more than other prey species. Jacobs’ index prey preference was used to investigate the importance of prey species to lion diets at three landscape scales: 1) Nyathi, 2) lion UD and 3) core lion UD. Lastly, prey population trends were investigated in Nyathi to provide an indication of possible changes in prey populations. Large prey species dominated the adjusted diets of lions in Main Camp-Colchester and Nyathi. However, when comparing the GPS carcass-derived lion diet estimate to the combined lion diet estimate, small prey were underestimated more often than large prey in the GPS carcass-derived lion diet estimate. Missed feeding events were therefore a function of prey body size. In addition, missed feeding events were also representative of the lion diets based on carcasses, with the tendency for species more often consumed to be missed more often in the diet record. However, even though small prey species were underestimated, they represented the minority of species consumed by lions and were predominantly avoided by lions in Nyathi. Lion prey preferences thus did not correlate to the declines in small prey species in Naythi, suggesting other potential drivers are important for small population trends in Nyathi. Lion predation cannot be ruled out as a driver of the decline in small prey species in Main Camp, due to different ecological conditions (e.g. vegetation density) in Main Camp compared to Nyathi, during the observed small prey population declines. Lion prey preferences in Nyathi revealed fine-scale variations in species specific preferences by lions, as well as site-specific differences in prey preferences when compared to published lion prey preference meta-analyses. These findings suggest that metaanalysis studies should be used as a guideline from which hypotheses about local predatorprey interactions can be developed rather than as an absolute measure of prey preference.
- Full Text:
- Date Issued: 2017
- Authors: Gerber, Amarein Judith
- Date: 2017
- Subjects: Wildlife conservation -- South Africa -- Addo Elephant National Park , Lion -- Behavior -- South Africa -- Addo Elephant National Park Lion -- Conservation -- South Africa -- Addo Elephant National Park
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14311 , vital:27542
- Description: Populations of small prey species (< 92 kg) can be regulated by competition, habitat-mediated responses, climate change, disease and predation. Populations of small prey species have declined in the Addo Elephant National Park Main Camp Section since the reintroduction of apex predators (lion and spotted hyaena). One possible explanation is predation by lion and spotted hyaena. However, small prey species are not generally considered preferred prey items of these predators, hence their contribution to predator diets needs to be explored. Global Positioning System (GPS) cluster analysis has emerged as a viable approach to locate lion kills for lion diet estimation in AENP, however this technique is known to bias diet estimates to large prey species. Understanding the impact of lion predation on populations of small prey in Main Camp therefore requires better estimates of lion diets. This study investigated the potential underestimation of small prey species in lion diet estimates by combining the data from scat analysis and carcasses located at GPS clusters. The adjusted lion diets were then used to investigate if the impact of lion predation could explain declines in small prey, by relating lion prey preferences to prey population trends in Nyathi. Using the results from Nyathi, it could then be inferred whether lions could have been responsible for the declines observed in Main Camp. Six GPS-collared lions provided location data used to construct individual movement paths, along which spatio-temporal clusters of GPS locations (n = 4896) were identified for ground investigation. Carcasses (n = 643) were recorded at the GPS clusters and scats (n = 256) were collected at GPS clusters with or without carcasses. Data from the located carcasses and scat collections were then used to create a history of feeding events for each collared lion in Main Camp-Colchester and Nyathi from a) carcasses alone or b) a combination of scats and carcasses, based on an estimated short and long lion throughout period. Relative prey availability was estimated based on camera trapping in Nyathi in high lion, low lion and no lion use areas, as lions may encounter some prey species more than other prey species. Jacobs’ index prey preference was used to investigate the importance of prey species to lion diets at three landscape scales: 1) Nyathi, 2) lion UD and 3) core lion UD. Lastly, prey population trends were investigated in Nyathi to provide an indication of possible changes in prey populations. Large prey species dominated the adjusted diets of lions in Main Camp-Colchester and Nyathi. However, when comparing the GPS carcass-derived lion diet estimate to the combined lion diet estimate, small prey were underestimated more often than large prey in the GPS carcass-derived lion diet estimate. Missed feeding events were therefore a function of prey body size. In addition, missed feeding events were also representative of the lion diets based on carcasses, with the tendency for species more often consumed to be missed more often in the diet record. However, even though small prey species were underestimated, they represented the minority of species consumed by lions and were predominantly avoided by lions in Nyathi. Lion prey preferences thus did not correlate to the declines in small prey species in Naythi, suggesting other potential drivers are important for small population trends in Nyathi. Lion predation cannot be ruled out as a driver of the decline in small prey species in Main Camp, due to different ecological conditions (e.g. vegetation density) in Main Camp compared to Nyathi, during the observed small prey population declines. Lion prey preferences in Nyathi revealed fine-scale variations in species specific preferences by lions, as well as site-specific differences in prey preferences when compared to published lion prey preference meta-analyses. These findings suggest that metaanalysis studies should be used as a guideline from which hypotheses about local predatorprey interactions can be developed rather than as an absolute measure of prey preference.
- Full Text:
- Date Issued: 2017
An intergrated continuous flow system for the manufacture of biodiesel from waste cooking oil using a heterogeneous acid catalyst and homogeneous base catalyst
- Authors: Mathe,Francis Matota
- Date: 2017
- Subjects: Biodiesel fuels industry , Catalysis , Vegetable oils as fuel
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44460 , vital:37837
- Description: The continuous flow production of biodiesel from waste cooking oil (WCO) was investigated in this study. Two different methods of biodiesel production were investigated. The first method involved the acid esterification of free fatty acids (FFAs). In the biodiesel community, the esterification of FFAs in WCO is usually regarded as the pre-treatment stage of biodiesel production using low-quality feedstock.The second method involved the transesterification of triglycerides in WCO. Homogeneous catalysts (NaOH or H2SO4) and heterogeneous catalysts (NaOH/ZnO, Sn/ZnO, Amberlyst-15, Amberlite-IRA 904, Fe/Bentonite and Amberlite IRN 78) were evaluated in the transesterification reaction. Catalyst screening was done using a batch reactor. NaOH gave a high úME content of 96.7% and was chosen as the optimum catalyst for the reaction.The main aim of the project was to make an integrated system that incorporates the esterification and transesterification reaction in the flow production of biodiesel using WCO. The system was developed using the conditions obtained from optimum studies of the separate reactions. Slight adjustments based on further experimental work were made to create an efficient system. The effect of excess methanol from the first step on the concentration of NaOH in the second phase was investigated. It was shown that the excess methanol decreases the concentration of the NaOH and this decreases the úMEs in the final mixture of biodiesel.
- Full Text:
- Date Issued: 2017
- Authors: Mathe,Francis Matota
- Date: 2017
- Subjects: Biodiesel fuels industry , Catalysis , Vegetable oils as fuel
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44460 , vital:37837
- Description: The continuous flow production of biodiesel from waste cooking oil (WCO) was investigated in this study. Two different methods of biodiesel production were investigated. The first method involved the acid esterification of free fatty acids (FFAs). In the biodiesel community, the esterification of FFAs in WCO is usually regarded as the pre-treatment stage of biodiesel production using low-quality feedstock.The second method involved the transesterification of triglycerides in WCO. Homogeneous catalysts (NaOH or H2SO4) and heterogeneous catalysts (NaOH/ZnO, Sn/ZnO, Amberlyst-15, Amberlite-IRA 904, Fe/Bentonite and Amberlite IRN 78) were evaluated in the transesterification reaction. Catalyst screening was done using a batch reactor. NaOH gave a high úME content of 96.7% and was chosen as the optimum catalyst for the reaction.The main aim of the project was to make an integrated system that incorporates the esterification and transesterification reaction in the flow production of biodiesel using WCO. The system was developed using the conditions obtained from optimum studies of the separate reactions. Slight adjustments based on further experimental work were made to create an efficient system. The effect of excess methanol from the first step on the concentration of NaOH in the second phase was investigated. It was shown that the excess methanol decreases the concentration of the NaOH and this decreases the úMEs in the final mixture of biodiesel.
- Full Text:
- Date Issued: 2017
Ant colony optimisation-based algorithms for optical burst switching networks
- Gravett, Andrew Scott, Gibbon, Timothy B
- Authors: Gravett, Andrew Scott , Gibbon, Timothy B
- Date: 2017
- Subjects: Distributed algorithms , Ants -- Behavior -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/18939 , vital:28757
- Description: This research developed two novel distributed algorithms inspired by Ant Colony Optimisation (ACO) for a solution to the problem of dynamic Routing and Wavelength Assignment (RWA) with wavelength continuity constraint in Optical Burst Switching (OBS) networks utilising both the traditional International Telecommunication Union (ITU) Fixed Grid Wavelength Division Multiplexing (WDM) and Flexible Spectrum scenarios. The growing demand for more bandwidth in optical networks require more efficient utilisation of available optical resources. OBS is a promising optical switching technique for the improved utilisation of optical network resources over the current optical circuit switching technique. The development of newer technologies has introduced higher rate transmissions and various modulation formats, however, introducing these technologies into the traditional ITU Fixed Grid does not efficiently utilise the available bandwidth. Flexible Spectrum is a promising approach offering a solution to the problem of improving bandwidth utilisation, which comes with a potential cost. Transmissions have the potential for impairment with respect to the increased traffic and lack of large channel spacing. Proposed routing algorithms should be aware of the linear and non-linear Physical Layer Impairments (PLIs) in order to operate closer to optimum performance. The OBS resource reservation protocol does not cater for the loss of transmissions, Burst Control Packets (BCPs) included, due to physical layer impairments. The protocol was adapted for use in Flexible Spectrum. Investigation of the use of a route and wavelength combination, from source to destination node pair, for the RWA process was proposed for ACO-based approaches to enforce the establishment and use of complete paths for greedy exploitation in Flexible Spectrum was conducted. The routing tuple for the RWA process is the tight coupling of a route and wavelength in combination intended to promote the greedy exploitation of successful paths for transmission requests. The application of the routing tuples differs from traditional ACO-based approaches and prompted the investigation of new pheromone calculation equations. The two novel proposed approaches were tested and experiments conducted comparing with and against existing algorithms (a simple greedy and an ACO-based algorithm) in a traditional ITU Fixed Grid and Flexible Spectrum scenario on three different network topologies. The proposed Flexible Spectrum Ant Colony (FSAC) approach had a markably improved performance over the existing algorithms in the ITU Fixed Grid WDM and Flexible Spectrum scenarios, while Upper Confidence Bound Routing and Wavelength Assignment (UCBRWA) algorithm was able to perform well in the traditional ITU Fixed Grid WDM scenario, but underperformed in the Flexible Spectrum scenario. The results show that the distributed ACO-based FSAC algorithm significantly improved the burst transmission success probability, providing a good solution in the Flexible Spectrum network environment undergoing transmission impairments.
- Full Text:
- Date Issued: 2017
- Authors: Gravett, Andrew Scott , Gibbon, Timothy B
- Date: 2017
- Subjects: Distributed algorithms , Ants -- Behavior -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/18939 , vital:28757
- Description: This research developed two novel distributed algorithms inspired by Ant Colony Optimisation (ACO) for a solution to the problem of dynamic Routing and Wavelength Assignment (RWA) with wavelength continuity constraint in Optical Burst Switching (OBS) networks utilising both the traditional International Telecommunication Union (ITU) Fixed Grid Wavelength Division Multiplexing (WDM) and Flexible Spectrum scenarios. The growing demand for more bandwidth in optical networks require more efficient utilisation of available optical resources. OBS is a promising optical switching technique for the improved utilisation of optical network resources over the current optical circuit switching technique. The development of newer technologies has introduced higher rate transmissions and various modulation formats, however, introducing these technologies into the traditional ITU Fixed Grid does not efficiently utilise the available bandwidth. Flexible Spectrum is a promising approach offering a solution to the problem of improving bandwidth utilisation, which comes with a potential cost. Transmissions have the potential for impairment with respect to the increased traffic and lack of large channel spacing. Proposed routing algorithms should be aware of the linear and non-linear Physical Layer Impairments (PLIs) in order to operate closer to optimum performance. The OBS resource reservation protocol does not cater for the loss of transmissions, Burst Control Packets (BCPs) included, due to physical layer impairments. The protocol was adapted for use in Flexible Spectrum. Investigation of the use of a route and wavelength combination, from source to destination node pair, for the RWA process was proposed for ACO-based approaches to enforce the establishment and use of complete paths for greedy exploitation in Flexible Spectrum was conducted. The routing tuple for the RWA process is the tight coupling of a route and wavelength in combination intended to promote the greedy exploitation of successful paths for transmission requests. The application of the routing tuples differs from traditional ACO-based approaches and prompted the investigation of new pheromone calculation equations. The two novel proposed approaches were tested and experiments conducted comparing with and against existing algorithms (a simple greedy and an ACO-based algorithm) in a traditional ITU Fixed Grid and Flexible Spectrum scenario on three different network topologies. The proposed Flexible Spectrum Ant Colony (FSAC) approach had a markably improved performance over the existing algorithms in the ITU Fixed Grid WDM and Flexible Spectrum scenarios, while Upper Confidence Bound Routing and Wavelength Assignment (UCBRWA) algorithm was able to perform well in the traditional ITU Fixed Grid WDM scenario, but underperformed in the Flexible Spectrum scenario. The results show that the distributed ACO-based FSAC algorithm significantly improved the burst transmission success probability, providing a good solution in the Flexible Spectrum network environment undergoing transmission impairments.
- Full Text:
- Date Issued: 2017
Anthropometric indicators in identifying malnutrition risk among children younger than two years in Motherwell, Nelson Mandela Metropolitan Municipality
- Authors: McLaren, Shawn William
- Date: 2017
- Subjects: Nutrition disorders in children -- South Africa -- Nelson Mandela Bay Municipality , Malnutrition in children -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19256 , vital:28811
- Description: Introduction: South Africa is burdened with a high prevalence of childhood malnutrition. The World Health Organisation (WHO) endorses weight for length (WFL) Z-scores and mid-upper arm circumference (MUAC) as tools for identifying children who are malnourished. The MUAC measurement offers many advantages for its use in community nutrition, and may aid in the early identification of malnourished children. More accurate and comprehensive data on child anthropometric status are needed in the Nelson Mandela Bay Health District (NMBHD), as well as assessment of the efficacy of using a simplified tool such as MUAC to screen for malnutrition. Aim: This study aimed to synthesise a profile of the nutritional status of children younger than two years old in Motherwell, Nelson Mandela Metropolitan Municipality (NMMM) to assess the value of MUAC as a predictor of malnutrition risk and develop malnutrition screening recommendations relevant to this population. Methods: This study followed a cross-sectional design using a quantitative approach. A convenience sample (n=419) of children below 24 months of age was selected from clinics and creches in Motherwell between October 2015 and February 2016 (Ethics approval: H15-HEA-DIET-002). Primary caregivers provided informed written consent for study participation. Trained fieldworkers performed anthropometric measurements according to standardised methods and completed a structured questionnaire. Data was described using means and standard deviations. Linear regression was used to assess relationships within the data. The MUAC’s ability to identify malnutrition was described using sensitivity and specificity probabilities. Results: Only 6% of the sample of children (n=23) were classified as stunted and 3% of the children (n=12) were severely stunted. The WHZ Z-score identified 0% (n=1) child with severe acute malnutrition (SAM), and 1% (n=3) children as MAM. The MUAC identified more children as SAM (2%) and MAM (3%). It was found that 16% of the children (n=65) were overweight or obese according to WHZ. It was found that there is a strong linear relationship between WHZ and MUAC (r=0.739). Using the least squares regression equation, a MUAC cut off value of 13,80cm for males and 13,5cm for females between six and 24 months old was projected. The male cut-off value has a 100% sensitivity and 94,5% specificity for MAM and SAM while the female MUAC cut off had a specificity of 96,4%. Low birth weight children had significantly (p<0.0005) lower mean WAZ and HAZ scores than normal birth weight children. Conclusions and recommendations The prevalence of overweight and obesity among children younger than two years was high in Motherwell, while stunting and wasting prevalence were lower than expected for the population. Raising the MUAC cut-off values from 12,5cm for MAM to 13,80cm for males and 13,47cm for females may increase the number of children younger than two years who are included in nutrition interventions. It is recommended that healthcare workers focus on breastfeeding and appropriate complementary feeding practices to reduce the risk of overweight in infants and young children.
- Full Text:
- Authors: McLaren, Shawn William
- Date: 2017
- Subjects: Nutrition disorders in children -- South Africa -- Nelson Mandela Bay Municipality , Malnutrition in children -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19256 , vital:28811
- Description: Introduction: South Africa is burdened with a high prevalence of childhood malnutrition. The World Health Organisation (WHO) endorses weight for length (WFL) Z-scores and mid-upper arm circumference (MUAC) as tools for identifying children who are malnourished. The MUAC measurement offers many advantages for its use in community nutrition, and may aid in the early identification of malnourished children. More accurate and comprehensive data on child anthropometric status are needed in the Nelson Mandela Bay Health District (NMBHD), as well as assessment of the efficacy of using a simplified tool such as MUAC to screen for malnutrition. Aim: This study aimed to synthesise a profile of the nutritional status of children younger than two years old in Motherwell, Nelson Mandela Metropolitan Municipality (NMMM) to assess the value of MUAC as a predictor of malnutrition risk and develop malnutrition screening recommendations relevant to this population. Methods: This study followed a cross-sectional design using a quantitative approach. A convenience sample (n=419) of children below 24 months of age was selected from clinics and creches in Motherwell between October 2015 and February 2016 (Ethics approval: H15-HEA-DIET-002). Primary caregivers provided informed written consent for study participation. Trained fieldworkers performed anthropometric measurements according to standardised methods and completed a structured questionnaire. Data was described using means and standard deviations. Linear regression was used to assess relationships within the data. The MUAC’s ability to identify malnutrition was described using sensitivity and specificity probabilities. Results: Only 6% of the sample of children (n=23) were classified as stunted and 3% of the children (n=12) were severely stunted. The WHZ Z-score identified 0% (n=1) child with severe acute malnutrition (SAM), and 1% (n=3) children as MAM. The MUAC identified more children as SAM (2%) and MAM (3%). It was found that 16% of the children (n=65) were overweight or obese according to WHZ. It was found that there is a strong linear relationship between WHZ and MUAC (r=0.739). Using the least squares regression equation, a MUAC cut off value of 13,80cm for males and 13,5cm for females between six and 24 months old was projected. The male cut-off value has a 100% sensitivity and 94,5% specificity for MAM and SAM while the female MUAC cut off had a specificity of 96,4%. Low birth weight children had significantly (p<0.0005) lower mean WAZ and HAZ scores than normal birth weight children. Conclusions and recommendations The prevalence of overweight and obesity among children younger than two years was high in Motherwell, while stunting and wasting prevalence were lower than expected for the population. Raising the MUAC cut-off values from 12,5cm for MAM to 13,80cm for males and 13,47cm for females may increase the number of children younger than two years who are included in nutrition interventions. It is recommended that healthcare workers focus on breastfeeding and appropriate complementary feeding practices to reduce the risk of overweight in infants and young children.
- Full Text:
Assessing the outcomes and consequences of large carnivore reintroductions to the Eastern Cape, South Africa
- Banasiak, Natalia Matgorzata
- Authors: Banasiak, Natalia Matgorzata
- Date: 2017
- Subjects: Carnivores -- Reintroduction , Wildlife reintroduction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/11963 , vital:27011
- Description: Reintroduction is a potentially powerful tool available to conservationists to cope with species population declines. Nonetheless, it is poorly understood and past reviews tend to indicate poor results. Reintroduction, under the sensu stricto IUCN definition, must have a primary objective of conservation; however species can be released to sites in their indigenous range (reintroduction sensu lato) to meet other objectives. The outcomes of these reintroductions s.l need to be assessed to determine how effectively they achieve their varied objectives. A Web of Science review revealed that only 32.1% of 131 publications on reintroduction provided clearly defined success criteria. Using economic, ecological, conservation and problem animal management objectives as reintroduction s.l. drivers, I developed context-dependent success definitions for each objective to use in reintroduction outcome assessments. These success criteria were then used to assess the reintroductions s.l. of large carnivores, namely lion, leopard, cheetah, African wild dog, spotted hyaena, and brown hyaena, to 16 private- and state-owned reserves in the Eastern Cape Province, South Africa. Ecotourism and ecological restoration were the most common objectives for the reintroduction of top predators to these reserves. Overall the reintroductions of large carnivores have been successful in meeting their objectives. Only African wild dogs have failed to establish in the province. Causes of objective-specific failures for the other species in some reserves included introductions of same-sex populations, lack of breeding events and changes in reserve management objectives. Assessments for leopard and brown hyaena were inconclusive due to lack of monitoring data. The reintroduction of large carnivores to the Eastern Cape Province has also resulted in the emergence of human-carnivore conflict on neighbouring properties. Carnivores have reportedly escaped from 8 reserves (61.5% of reserves) in the Eastern Cape. A total of 75 conflict events on 68 neighbouring properties (36.7% of neighbouring properties) have been reported. There is a major gap in research around conflict resulting from carnivore reintroductions and future research is required to fully understand the situation in the province in order to develop effective mitigation methods. An adaptive management approach to reintroductions is encouraged to improve monitoring and ensure reintroductions continue to meet their objectives. Furthermore, emerging consequences, such as human-wildlife conflict, and related mitigation strategies should be incorporated into management of reintroduced populations. Communities surrounding reintroduction sites should be educated on lifting baselines where conflict-causing species are recovering to ensure continued success of reintroduction undertakings. National management plans should be developed for all large carnivore species to improve the conservation value of small, fenced reserves that are typical of South African conservation, through a managed metapopulation approach. Management plans should include social, political, and economic factors that can influence the success of reintroductions and ultimate conservation outcomes.
- Full Text:
- Date Issued: 2017
- Authors: Banasiak, Natalia Matgorzata
- Date: 2017
- Subjects: Carnivores -- Reintroduction , Wildlife reintroduction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/11963 , vital:27011
- Description: Reintroduction is a potentially powerful tool available to conservationists to cope with species population declines. Nonetheless, it is poorly understood and past reviews tend to indicate poor results. Reintroduction, under the sensu stricto IUCN definition, must have a primary objective of conservation; however species can be released to sites in their indigenous range (reintroduction sensu lato) to meet other objectives. The outcomes of these reintroductions s.l need to be assessed to determine how effectively they achieve their varied objectives. A Web of Science review revealed that only 32.1% of 131 publications on reintroduction provided clearly defined success criteria. Using economic, ecological, conservation and problem animal management objectives as reintroduction s.l. drivers, I developed context-dependent success definitions for each objective to use in reintroduction outcome assessments. These success criteria were then used to assess the reintroductions s.l. of large carnivores, namely lion, leopard, cheetah, African wild dog, spotted hyaena, and brown hyaena, to 16 private- and state-owned reserves in the Eastern Cape Province, South Africa. Ecotourism and ecological restoration were the most common objectives for the reintroduction of top predators to these reserves. Overall the reintroductions of large carnivores have been successful in meeting their objectives. Only African wild dogs have failed to establish in the province. Causes of objective-specific failures for the other species in some reserves included introductions of same-sex populations, lack of breeding events and changes in reserve management objectives. Assessments for leopard and brown hyaena were inconclusive due to lack of monitoring data. The reintroduction of large carnivores to the Eastern Cape Province has also resulted in the emergence of human-carnivore conflict on neighbouring properties. Carnivores have reportedly escaped from 8 reserves (61.5% of reserves) in the Eastern Cape. A total of 75 conflict events on 68 neighbouring properties (36.7% of neighbouring properties) have been reported. There is a major gap in research around conflict resulting from carnivore reintroductions and future research is required to fully understand the situation in the province in order to develop effective mitigation methods. An adaptive management approach to reintroductions is encouraged to improve monitoring and ensure reintroductions continue to meet their objectives. Furthermore, emerging consequences, such as human-wildlife conflict, and related mitigation strategies should be incorporated into management of reintroduced populations. Communities surrounding reintroduction sites should be educated on lifting baselines where conflict-causing species are recovering to ensure continued success of reintroduction undertakings. National management plans should be developed for all large carnivore species to improve the conservation value of small, fenced reserves that are typical of South African conservation, through a managed metapopulation approach. Management plans should include social, political, and economic factors that can influence the success of reintroductions and ultimate conservation outcomes.
- Full Text:
- Date Issued: 2017
Assessment of the host properties of selected optically pure, racemic and achiral compounds
- Authors: Jooste, Daniel Victor
- Date: 2017
- Subjects: Organic compounds -- Synthesis Cyclic compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/18826 , vital:28735
- Description: This study focussed on the synthesis and host properties of four different broad categories of potential host compounds, namely optically active and racemic TADDOL [(4R,5R)-α,α,α’,α’-tetraphenyl-1,3-dioxolane-4,5-dimethanol] and derivatives, TTFOL [(3R,4R)-2,2,5,5-tetraphenyltetrahydrofuran-3,4-diol], amino acid ester-derived compounds [(S)-4-(2-amino-3-hydroxy-3,3-diphenylpropyl)phenol], and compounds derived from xanthone [9-amino-9-phenylxanthene and 1,2-bis(9-phenyl-9H-xanthen-9-yl)hydrazine]. The potential hosts were recrystallized from a range of possible guest species and the resulting solids analysed by 1H-NMR spectroscopy. If inclusion was observed by this technique, the complexes were analysed further using single crystal X-ray techniques and thermal experiments where possible. Competition studies were carried out where these were deemed appropriate. Optically active and racemic TADDOLs were synthesized using L-(+) and DL-(±)-tartaric acid respectively. Two further derivatives were prepared whereby the hydroxyl groups were substituted for chlorine and azide in order to assess the effect of this change on the inclusion ability. Both the optically active and racemic TADDOLs displayed similar host abilities, complexing with guests with 1:1 host:guest ratios as determined through 1H-NMR spectroscopy. Competition experiments showed that both forms of TADDOL exhibited similar guest preferences for pyridine and the methylpyridine isomers. Pyridine however was preferred over 2-methylpyridine by optically active TADDOL while the racemic form preferred this methyl-substituted guest over pyridine. Thermal analysis studies showed, surprisingly, that the TADDOL complexes containing pyridine had higher relative thermal stabilities than those containing the methylpyridines, whether the host was optically active or not. The preference order of these hosts for these guests can, therefore, not be used as a predictor for the relative thermal stability of the complexes. TTFOL was found to include only ethanol, 2-methylpyridine and dioxane from the range of guest species used; the complex with dioxane did not produce X-ray quality crystals. The L-tyrosine derivative, (S)-4-(2-amino-3-hydroxy-3,3-diphenylpropyl)phenol, was an ineffective host incapable of including any of the guests used in these experiments. The two xanthone derivatives, 9-amino-9-phenylxanthene and 1,2-bis(9-phenyl-9H-xanthen-9-yl)hydrazine each formed complexes with one guest species (morpholine and DMF, respectively).
- Full Text:
- Date Issued: 2017
- Authors: Jooste, Daniel Victor
- Date: 2017
- Subjects: Organic compounds -- Synthesis Cyclic compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/18826 , vital:28735
- Description: This study focussed on the synthesis and host properties of four different broad categories of potential host compounds, namely optically active and racemic TADDOL [(4R,5R)-α,α,α’,α’-tetraphenyl-1,3-dioxolane-4,5-dimethanol] and derivatives, TTFOL [(3R,4R)-2,2,5,5-tetraphenyltetrahydrofuran-3,4-diol], amino acid ester-derived compounds [(S)-4-(2-amino-3-hydroxy-3,3-diphenylpropyl)phenol], and compounds derived from xanthone [9-amino-9-phenylxanthene and 1,2-bis(9-phenyl-9H-xanthen-9-yl)hydrazine]. The potential hosts were recrystallized from a range of possible guest species and the resulting solids analysed by 1H-NMR spectroscopy. If inclusion was observed by this technique, the complexes were analysed further using single crystal X-ray techniques and thermal experiments where possible. Competition studies were carried out where these were deemed appropriate. Optically active and racemic TADDOLs were synthesized using L-(+) and DL-(±)-tartaric acid respectively. Two further derivatives were prepared whereby the hydroxyl groups were substituted for chlorine and azide in order to assess the effect of this change on the inclusion ability. Both the optically active and racemic TADDOLs displayed similar host abilities, complexing with guests with 1:1 host:guest ratios as determined through 1H-NMR spectroscopy. Competition experiments showed that both forms of TADDOL exhibited similar guest preferences for pyridine and the methylpyridine isomers. Pyridine however was preferred over 2-methylpyridine by optically active TADDOL while the racemic form preferred this methyl-substituted guest over pyridine. Thermal analysis studies showed, surprisingly, that the TADDOL complexes containing pyridine had higher relative thermal stabilities than those containing the methylpyridines, whether the host was optically active or not. The preference order of these hosts for these guests can, therefore, not be used as a predictor for the relative thermal stability of the complexes. TTFOL was found to include only ethanol, 2-methylpyridine and dioxane from the range of guest species used; the complex with dioxane did not produce X-ray quality crystals. The L-tyrosine derivative, (S)-4-(2-amino-3-hydroxy-3,3-diphenylpropyl)phenol, was an ineffective host incapable of including any of the guests used in these experiments. The two xanthone derivatives, 9-amino-9-phenylxanthene and 1,2-bis(9-phenyl-9H-xanthen-9-yl)hydrazine each formed complexes with one guest species (morpholine and DMF, respectively).
- Full Text:
- Date Issued: 2017
Benthic algal communities of shallow reefs in the Eastern Cape: availability of abalone habitat
- Authors: Witte, Andrew Dennis
- Date: 2017
- Subjects: Reef ecology -- South Africa -- Eastern Cape Abalone fisheries -- Habitat -- South Africa -- Eastern Cape , Algal communities -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12032 , vital:27021
- Description: Marine ranching has been identified as an alternative to traditional aquacultural rearing and growing organisms for consumption. In the Eastern Cape, abalone ranching is a new and experimental industry. The aims of the research were to: first develop a GIS model to assist management in site selection for abalone seeding; and secondly to develop and standardize the sampling methodology in order to ground truth the sites, and assist in the monitoring and habitat identification of abalone. The GIS model developed in Chapter 3 was created using an unsupervised classification and fuzzy logic approach. Both vector and raster datasets were utilized to represent 7 different layers. Predominantly satellite imagery was used to classify the different substrate groups according to pixel colour signatures. The basic process was to apply a fuzzy rule set (membership) to rasters which gave an output raster (Fuzzification). The membership output rasters were overlaid which creates a single model output. It was found that model accuracy increased significantly as more layers were overlaid, due to the high variability within each of the individual layers. Model ground-truthing showed a strong and significant correlation (r2 = 0.91; p < 0.001) between the model outputs and actual site suitability based on in situ evaluation. Chapter 4 describes the investigation towards the optimal sampling methods for abalone ranching habitat assessments. Both destructive sampling methods and imagery methods were considered as methods of data collection. The study also evaluated whether quadrat and transects were going to be suitable methods to assess sites, and what size or length respectively they should be to collect the appropriate data. Transect length showed great variation according to the factor assessed. A transect of 15 metres was found to be optimal. Abalone counts showed no significant (p = 0.1) change in the Coefficent of Variance (CV) for transect lengths greater than 15m, and had a mean of 0.2 abalone per metre. Quadrat size showed a significant difference in functional group richness between quadrat sizes of 0.0625m2, and 0.25m2 but no difference between 0.25m2 and 1m2 quadrats for both scape and photographic quadrats. It was also found that between 5 and 10 replicates (p = 0.08) represents the functional groups appropriately using quadrats and that a 0.25m2 quadrat is most suitable for sampling. Chapter 5 describes the benthic community structure of Cape Recife shallow water reefs. Using the standardized methodology previously mentioned, 45 sites were assessed to identify the community structure. These sites were grouped into 5 different groups influenced by depth and substrate, as well as functional group composition according to a Wards classification. The community structure showed that depth and substrate play a significant role (p < 0.05) in the community type. There is also a significant relationship (p < 0.05) between complexity, rugosity, abalone presence and substrate. During this study the basic protocols for site selection and benthic community monitoring have been developed to support the abalone ranching initiative in the Cape Recife area. It has also provided a baseline of the benthic community in the ranching concession area which will be used as a benchmark for future monitoring efforts. The site selection, sampling, and monitoring methods developed during the course of this work have now been rolled out as Standard Operating Procedures for the ranching programme in this area.
- Full Text:
- Date Issued: 2017
- Authors: Witte, Andrew Dennis
- Date: 2017
- Subjects: Reef ecology -- South Africa -- Eastern Cape Abalone fisheries -- Habitat -- South Africa -- Eastern Cape , Algal communities -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12032 , vital:27021
- Description: Marine ranching has been identified as an alternative to traditional aquacultural rearing and growing organisms for consumption. In the Eastern Cape, abalone ranching is a new and experimental industry. The aims of the research were to: first develop a GIS model to assist management in site selection for abalone seeding; and secondly to develop and standardize the sampling methodology in order to ground truth the sites, and assist in the monitoring and habitat identification of abalone. The GIS model developed in Chapter 3 was created using an unsupervised classification and fuzzy logic approach. Both vector and raster datasets were utilized to represent 7 different layers. Predominantly satellite imagery was used to classify the different substrate groups according to pixel colour signatures. The basic process was to apply a fuzzy rule set (membership) to rasters which gave an output raster (Fuzzification). The membership output rasters were overlaid which creates a single model output. It was found that model accuracy increased significantly as more layers were overlaid, due to the high variability within each of the individual layers. Model ground-truthing showed a strong and significant correlation (r2 = 0.91; p < 0.001) between the model outputs and actual site suitability based on in situ evaluation. Chapter 4 describes the investigation towards the optimal sampling methods for abalone ranching habitat assessments. Both destructive sampling methods and imagery methods were considered as methods of data collection. The study also evaluated whether quadrat and transects were going to be suitable methods to assess sites, and what size or length respectively they should be to collect the appropriate data. Transect length showed great variation according to the factor assessed. A transect of 15 metres was found to be optimal. Abalone counts showed no significant (p = 0.1) change in the Coefficent of Variance (CV) for transect lengths greater than 15m, and had a mean of 0.2 abalone per metre. Quadrat size showed a significant difference in functional group richness between quadrat sizes of 0.0625m2, and 0.25m2 but no difference between 0.25m2 and 1m2 quadrats for both scape and photographic quadrats. It was also found that between 5 and 10 replicates (p = 0.08) represents the functional groups appropriately using quadrats and that a 0.25m2 quadrat is most suitable for sampling. Chapter 5 describes the benthic community structure of Cape Recife shallow water reefs. Using the standardized methodology previously mentioned, 45 sites were assessed to identify the community structure. These sites were grouped into 5 different groups influenced by depth and substrate, as well as functional group composition according to a Wards classification. The community structure showed that depth and substrate play a significant role (p < 0.05) in the community type. There is also a significant relationship (p < 0.05) between complexity, rugosity, abalone presence and substrate. During this study the basic protocols for site selection and benthic community monitoring have been developed to support the abalone ranching initiative in the Cape Recife area. It has also provided a baseline of the benthic community in the ranching concession area which will be used as a benchmark for future monitoring efforts. The site selection, sampling, and monitoring methods developed during the course of this work have now been rolled out as Standard Operating Procedures for the ranching programme in this area.
- Full Text:
- Date Issued: 2017
Characterization of a glycated gelatin model to explore the therapeutic properties of macrofungi in diabetic wound healing: an in vitro study
- Authors: Pringle, Nadine Alex
- Date: 2017
- Subjects: Diabetes -- Animal models Chronic diseases -- Age factors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/11992 , vital:27017
- Description: Diabetic wounds frequently undergo impaired and prolonged wound healing due to a multitude of factors including hypoxia, impaired angiogenesis, hyperglycaemia, formation of ROS and AGEs, and infection - all of which may lead to cellular dysfunction. To date, however, treatment options for individuals suffering from impaired diabetic wound healing are limited, non-specific, and generally unsuccessful. The search for new and effective treatment strategies is severely hampered by the availability of adequately characterized screening models which comprehensively mimic the complexity of the diabetic wound healing process. In order to explore natural products as potential therapeutics to treat diabetic wounds and to encourage more research on this topic, this study sought out to develop and characterize a more convenient and cost effective in vitro screening assay which mimics the effects of protein glycation on the healing process of diabetic wounds. As proof of principal, this model was subsequently used to screen the potential of five wild mushroom species (P. tinctorius, R. capensis, B. badius, P. ostreatus and G. lucidum) as suitable diabetic wound healing therapies. The glycated gelatin model developed during this study was found to suitably mimic the diabetic state as it successfully simulated the major cellular dysfunctions in macrophages (NO production, phagocytosis, macrophage polarization, NF-ĸB translocation and COX-2 expression) and fibroblasts (proliferation and migration) documented during diabetic wound healing. Together these findings provide confidence that the model may serve as a valuable tool to study the poorly understood mechanisms which characterize cellular dysfunction in response to AGE accumulation and also to aid the identification of novel therapeutic agents to treat this pathology. Screening a number of mushroom extracts revealed that the ethanol extracts of R. capensis and P. ostreatus had the greatest potential for attenuating chronic inflammation due to their ability to promote macrophage phagocytosis, increased M2 activation (R. capensis) and decreased M1 activation (P. ostreatus) as well as reduced COX-2 expression while the water extract of G. lucidum proved to be the most promising candidate for stimulating fibroplasia as it was the most successful at promoting both fibroblast proliferation and migration. Different mushroom species were thus shown to promote different stages of the wound healing process providing sufficient evidence to support further studies related to the use of macrofungi as therapeutic agents in the search for more cost-effective and efficient treatment strategies for impaired diabetic wound healing.
- Full Text:
- Date Issued: 2017
- Authors: Pringle, Nadine Alex
- Date: 2017
- Subjects: Diabetes -- Animal models Chronic diseases -- Age factors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/11992 , vital:27017
- Description: Diabetic wounds frequently undergo impaired and prolonged wound healing due to a multitude of factors including hypoxia, impaired angiogenesis, hyperglycaemia, formation of ROS and AGEs, and infection - all of which may lead to cellular dysfunction. To date, however, treatment options for individuals suffering from impaired diabetic wound healing are limited, non-specific, and generally unsuccessful. The search for new and effective treatment strategies is severely hampered by the availability of adequately characterized screening models which comprehensively mimic the complexity of the diabetic wound healing process. In order to explore natural products as potential therapeutics to treat diabetic wounds and to encourage more research on this topic, this study sought out to develop and characterize a more convenient and cost effective in vitro screening assay which mimics the effects of protein glycation on the healing process of diabetic wounds. As proof of principal, this model was subsequently used to screen the potential of five wild mushroom species (P. tinctorius, R. capensis, B. badius, P. ostreatus and G. lucidum) as suitable diabetic wound healing therapies. The glycated gelatin model developed during this study was found to suitably mimic the diabetic state as it successfully simulated the major cellular dysfunctions in macrophages (NO production, phagocytosis, macrophage polarization, NF-ĸB translocation and COX-2 expression) and fibroblasts (proliferation and migration) documented during diabetic wound healing. Together these findings provide confidence that the model may serve as a valuable tool to study the poorly understood mechanisms which characterize cellular dysfunction in response to AGE accumulation and also to aid the identification of novel therapeutic agents to treat this pathology. Screening a number of mushroom extracts revealed that the ethanol extracts of R. capensis and P. ostreatus had the greatest potential for attenuating chronic inflammation due to their ability to promote macrophage phagocytosis, increased M2 activation (R. capensis) and decreased M1 activation (P. ostreatus) as well as reduced COX-2 expression while the water extract of G. lucidum proved to be the most promising candidate for stimulating fibroplasia as it was the most successful at promoting both fibroblast proliferation and migration. Different mushroom species were thus shown to promote different stages of the wound healing process providing sufficient evidence to support further studies related to the use of macrofungi as therapeutic agents in the search for more cost-effective and efficient treatment strategies for impaired diabetic wound healing.
- Full Text:
- Date Issued: 2017
Development of a liposomal acyclovir mucoadhesive film
- Authors: Nalungwe, Sarah
- Date: 2017
- Subjects: Clinical pharmacology , Liposomes Nanomedicine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14212 , vital:27451
- Description: Acyclovir is a synthetic purine nucleoside analogue with in vitro and in vivo inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella-zoster virus (VZV). The efficacy of oral acyclovir is limited as a result of its low bioavailability (15-30%) as it is poorly water soluble and therefore requires a frequent dosing regimen. When orally administered, peak plasma concentration occurs after 1.5–2.5 hours, while its elimination half-life is approximately 2-3 hours. Acyclovir displays poor solubility in water and in lipid bilayers, which leads to poor drug levels at target sites after oral, local, or parenteral administration. In order to improve this lack of solubility, novel amphiphilic derivatives have been designed to form nanoparticles, which allow for the efficient encapsulation of this hydrophobic antiviral agent. Reformulation of drugs in liposomes has provided an opportunity to enhance the therapeutic indices of various agents mainly via alteration of their bio-distribution. Liposomal drug delivery systems have received considerable attention due to their immense advantages which include, effective encapsulation of both small and large molecules that have a wide range of hydrophobicity levels and pKa values, prolonging and targeting release of therapeutic agents by modification of liposomal surface and also minimising clinical drug dose thus reducing toxicity effects. Liposomes exhibit a number of special biological characteristics, including specific interactions with biological membranes and various cells, hence, liposomes are used as biocompatible carriers to improve delivery properties across mucus membranes. Mucoadhesive dosage forms may be designed to enable prolonged retention at the site of application, providing a controlled rate of drug release for improved therapeutic outcome. The aim of this study was to develop an acyclovir liposomal mucoadhesive film by actively encapsulating acyclovir into liposomes and preparing a mucoadhesive film to optimise delivery of acyclovir liposomes at target sites. To actively encapsulate acyclovir and prepare the acyclovir-containing liposomes, a comprehensive statistical methodology was used in optimising the liposome formulation to encapsulate acyclovir. Central composite design was used as the response surface methodology statistical tool to design and develop an optimised method for active encapsulation of acyclovir into liposomes. The predicted optimised encapsulation parameters were incubation temperature of 60 °C and incubation time of 45 minutes. The mean percentage encapsulation calculated was 27.72%. The overall average size of the liposomes was 99.5 nm with a narrow distribution polydispersity index of 0.105 and were physically characterised as small unilamellar vesicles which possessed an average zeta potential of -45.6 mV. High Performance Liquid Chromatography (HPLC) was used to analyse and determine acyclovir drug content in the liposomes and drug release pattern from the mucoadhesive film. Polyvinyl-pyrrolidone (PVP) and Polyethylene glycol (PEG) were used in the preparation of mucoadhesive film, in which the acyclovir encapsulated liposomes were incorporated. The average amount of acyclovir drug content quantified to be in 4 cm2 of the mucoadhesive film was 36.8543 μg. The average tensile strength of the mucoadhesive film was determined to be 3.06 N/mm2 with an elongation percentage of 4.54%. The toughness of the film was 71.50 N.mm and the force required to rupture film was 16.49 N. The work and maximum force required to detach the mucoadhesive film from the glass side was 2.58 N.mm and 11615.32 mN, respectively. A Franz diffusion cell was used to perform acyclovir drug release studies from the mucoadhesive film and a commercial brand of acyclovir cream (Acitop®). Percentage acyclovir drug release from the film and cream was plotted against time using Sigmaplot® software version 13 following First order, Peppas, Hixon and Crowell, Higuchi (Square Root Time) and Bakers and Lonsdale mathematical models. The mucoadhesive film acyclovir attained the highest correlation coefficient r2 of 0.9879 following the Baker & Lonsdale mathematical model which describes controlled drug release from spherical matrices hence fits the model as the acyclovir is encapsulated in liposomes which are incorporated in the polymer mucoadhesive film. And the acyclovir cream (Acitop®) attained the highest correlation coefficient r2 of 0.9944 following the Peppas mathematical model. The Peppas model has been used to describe drug release from various release dosage forms when there is more than one type of dosage release or when release mechanism is not well known. One assumption of this model is that drug release occurs in one dimension, which is a suitable release profile for the cream as it is absorbed through the skin in one dimension when applied topically. There was significant difference between the drug release data for the mucoadhesive film and the acyclovir cream (Acitop®). A physically stable mucoadhesive film containing acyclovir-loaded liposomes was developed.
- Full Text:
- Date Issued: 2017
- Authors: Nalungwe, Sarah
- Date: 2017
- Subjects: Clinical pharmacology , Liposomes Nanomedicine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14212 , vital:27451
- Description: Acyclovir is a synthetic purine nucleoside analogue with in vitro and in vivo inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella-zoster virus (VZV). The efficacy of oral acyclovir is limited as a result of its low bioavailability (15-30%) as it is poorly water soluble and therefore requires a frequent dosing regimen. When orally administered, peak plasma concentration occurs after 1.5–2.5 hours, while its elimination half-life is approximately 2-3 hours. Acyclovir displays poor solubility in water and in lipid bilayers, which leads to poor drug levels at target sites after oral, local, or parenteral administration. In order to improve this lack of solubility, novel amphiphilic derivatives have been designed to form nanoparticles, which allow for the efficient encapsulation of this hydrophobic antiviral agent. Reformulation of drugs in liposomes has provided an opportunity to enhance the therapeutic indices of various agents mainly via alteration of their bio-distribution. Liposomal drug delivery systems have received considerable attention due to their immense advantages which include, effective encapsulation of both small and large molecules that have a wide range of hydrophobicity levels and pKa values, prolonging and targeting release of therapeutic agents by modification of liposomal surface and also minimising clinical drug dose thus reducing toxicity effects. Liposomes exhibit a number of special biological characteristics, including specific interactions with biological membranes and various cells, hence, liposomes are used as biocompatible carriers to improve delivery properties across mucus membranes. Mucoadhesive dosage forms may be designed to enable prolonged retention at the site of application, providing a controlled rate of drug release for improved therapeutic outcome. The aim of this study was to develop an acyclovir liposomal mucoadhesive film by actively encapsulating acyclovir into liposomes and preparing a mucoadhesive film to optimise delivery of acyclovir liposomes at target sites. To actively encapsulate acyclovir and prepare the acyclovir-containing liposomes, a comprehensive statistical methodology was used in optimising the liposome formulation to encapsulate acyclovir. Central composite design was used as the response surface methodology statistical tool to design and develop an optimised method for active encapsulation of acyclovir into liposomes. The predicted optimised encapsulation parameters were incubation temperature of 60 °C and incubation time of 45 minutes. The mean percentage encapsulation calculated was 27.72%. The overall average size of the liposomes was 99.5 nm with a narrow distribution polydispersity index of 0.105 and were physically characterised as small unilamellar vesicles which possessed an average zeta potential of -45.6 mV. High Performance Liquid Chromatography (HPLC) was used to analyse and determine acyclovir drug content in the liposomes and drug release pattern from the mucoadhesive film. Polyvinyl-pyrrolidone (PVP) and Polyethylene glycol (PEG) were used in the preparation of mucoadhesive film, in which the acyclovir encapsulated liposomes were incorporated. The average amount of acyclovir drug content quantified to be in 4 cm2 of the mucoadhesive film was 36.8543 μg. The average tensile strength of the mucoadhesive film was determined to be 3.06 N/mm2 with an elongation percentage of 4.54%. The toughness of the film was 71.50 N.mm and the force required to rupture film was 16.49 N. The work and maximum force required to detach the mucoadhesive film from the glass side was 2.58 N.mm and 11615.32 mN, respectively. A Franz diffusion cell was used to perform acyclovir drug release studies from the mucoadhesive film and a commercial brand of acyclovir cream (Acitop®). Percentage acyclovir drug release from the film and cream was plotted against time using Sigmaplot® software version 13 following First order, Peppas, Hixon and Crowell, Higuchi (Square Root Time) and Bakers and Lonsdale mathematical models. The mucoadhesive film acyclovir attained the highest correlation coefficient r2 of 0.9879 following the Baker & Lonsdale mathematical model which describes controlled drug release from spherical matrices hence fits the model as the acyclovir is encapsulated in liposomes which are incorporated in the polymer mucoadhesive film. And the acyclovir cream (Acitop®) attained the highest correlation coefficient r2 of 0.9944 following the Peppas mathematical model. The Peppas model has been used to describe drug release from various release dosage forms when there is more than one type of dosage release or when release mechanism is not well known. One assumption of this model is that drug release occurs in one dimension, which is a suitable release profile for the cream as it is absorbed through the skin in one dimension when applied topically. There was significant difference between the drug release data for the mucoadhesive film and the acyclovir cream (Acitop®). A physically stable mucoadhesive film containing acyclovir-loaded liposomes was developed.
- Full Text:
- Date Issued: 2017
Devulcanization of model compounds by a variety of diphenyldisulfides
- Authors: Boyce, Annemè
- Date: 2017
- Subjects: Rubber -- Recycling Rubber, Reclaimed , Rubber -- Standards -- South Africa Rubber -- Research Chromatographic analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14730 , vital:27834
- Description: Improvements to the properties of recycled rubber, by developing a more selective breakdown process, is an important issue and a global challenge. Devulcanization is the most promising way to achieve this. It is a process which aims to totally or partially cleave monosulfidic (C-S-C), disulfidic (C-S-S-C) and polysulfidic (C-Sx-C) crosslinks of vulcanized rubber. In this study, the devulcanization of sulfur-vulcanized natural rubber with a variety of diphenyldisulfides has been studied using 2,3-dimethyl-2-butene and squalene as model compounds, vulcanized by sulfur and 2-bisbenzothiazole-2,2’-disulfide. 2-aminodiphenyldisulfide; 4-amino-diphenyldisulfide; bis(2-benzamido-)diphenyldisulfide and 2,2’-bithiosalicylic acid were used as aromatic disulfides devulcanization agents. Thermal analysis was used to investigate interactions between various combinations of curatives in the vulcanization systems in the absence of model compounds. Thermogravimetric analysis was used to detect mass changes during vulcanization and whether the samples decompose/evaporate so as not to contaminate differential scanning calorimetry instrumentation. Differential scanning calorimetry was used to investigate reactions occurring between curatives. Comparison of reversing and non-reversing signals in modulated experiments are suggestive of reactions between devulcanization agents and sulfur, and accelerators Vulcanization of the model compounds were performed in 10m evacuated sealed glass ampoules placed in an oil bath at 160 °C and agitated for the duration of vulcanization. After 60 min the ampoules were removed and quenched. These were then devulcanized by exposure to a devulcanization agent in a sealed ampoule at 180 for 60 min. Crosslinked 2,3-dimethyl-2-butene species were isolated and analysed by reversed phase high performance liquid chromatography. Particular attention was paid to changes in the number of sulfur atoms in the crosslinks. Results indicate that of the devulcanization agents tested 4-amino-diphenyldisulfide was the most effective. No detrimental effect on devulcanization efficiency was caused by the substitution of a basic amino group with an acidic carboxylic acid group Gel permeation chromatography was performed on devulcanized squalene crosslinks using a tetrahydrofuran eluent. GPC investigations with squalene were less effective than HPLC experiments with 2,3-dimethyl-2-butene at evaluating the relative efficiency of individual devulcanization agents. Results were, however, consistent with 4-amino-diphenyldisulfide again being the most efficient devulcanization agent.
- Full Text:
- Date Issued: 2017
- Authors: Boyce, Annemè
- Date: 2017
- Subjects: Rubber -- Recycling Rubber, Reclaimed , Rubber -- Standards -- South Africa Rubber -- Research Chromatographic analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14730 , vital:27834
- Description: Improvements to the properties of recycled rubber, by developing a more selective breakdown process, is an important issue and a global challenge. Devulcanization is the most promising way to achieve this. It is a process which aims to totally or partially cleave monosulfidic (C-S-C), disulfidic (C-S-S-C) and polysulfidic (C-Sx-C) crosslinks of vulcanized rubber. In this study, the devulcanization of sulfur-vulcanized natural rubber with a variety of diphenyldisulfides has been studied using 2,3-dimethyl-2-butene and squalene as model compounds, vulcanized by sulfur and 2-bisbenzothiazole-2,2’-disulfide. 2-aminodiphenyldisulfide; 4-amino-diphenyldisulfide; bis(2-benzamido-)diphenyldisulfide and 2,2’-bithiosalicylic acid were used as aromatic disulfides devulcanization agents. Thermal analysis was used to investigate interactions between various combinations of curatives in the vulcanization systems in the absence of model compounds. Thermogravimetric analysis was used to detect mass changes during vulcanization and whether the samples decompose/evaporate so as not to contaminate differential scanning calorimetry instrumentation. Differential scanning calorimetry was used to investigate reactions occurring between curatives. Comparison of reversing and non-reversing signals in modulated experiments are suggestive of reactions between devulcanization agents and sulfur, and accelerators Vulcanization of the model compounds were performed in 10m evacuated sealed glass ampoules placed in an oil bath at 160 °C and agitated for the duration of vulcanization. After 60 min the ampoules were removed and quenched. These were then devulcanized by exposure to a devulcanization agent in a sealed ampoule at 180 for 60 min. Crosslinked 2,3-dimethyl-2-butene species were isolated and analysed by reversed phase high performance liquid chromatography. Particular attention was paid to changes in the number of sulfur atoms in the crosslinks. Results indicate that of the devulcanization agents tested 4-amino-diphenyldisulfide was the most effective. No detrimental effect on devulcanization efficiency was caused by the substitution of a basic amino group with an acidic carboxylic acid group Gel permeation chromatography was performed on devulcanized squalene crosslinks using a tetrahydrofuran eluent. GPC investigations with squalene were less effective than HPLC experiments with 2,3-dimethyl-2-butene at evaluating the relative efficiency of individual devulcanization agents. Results were, however, consistent with 4-amino-diphenyldisulfide again being the most efficient devulcanization agent.
- Full Text:
- Date Issued: 2017
Effect of graphitization on the static mechanical properties of service exposed ASTM A516 Gr. 65 steam pipe metal
- Authors: Du Preez, Christiaan
- Date: 2017
- Subjects: Graphitization Steam-pipes -- Mechanical properties
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22277 , vital:29933
- Description: The focus of this research project is to establish what effect graphitization has on the static mechanical properties of service exposed ASTM A516 Grade 65 steam pipe material, which operated for prolonged periods above 425 ̊C. The research study was conducted on three graphitized service exposed steam pipe weldment samples and on a newly welded and post weld heat treated sample with graphitized service exposed steam pipe material. Macro samples were removed from each of the samples at two positions and these were evaluated with regard to graphite nodule size, nearest neighbour spacing and % planar graphitization in the parent pipe and HAZ regions on either side of the welds. It was found on all of the service exposed samples that the graphite nodules of the HAZ regions have a smaller median nodule size, smaller median nearest neighbour spacing and increased % planar graphitization in comparison to the parent pipe material. The service expose parent pipe material on either side of the weldments of the respective samples was chemically analyzed. This was done with the focus being on the deoxidizing element content (Si and Al) of the respective parent pipe regions and to what extent these elements influenced the development of planar graphitization in these regions. No correlation could be identified between the level of deoxidizing elements and the levels of % planar graphitization in the parent pipe material. Tensile and Charpy impact samples were removed from the respective service exposed samples parent material on either side of the weld and from the HAZ regions on the side with the highest levels of planar graphitization. These samples were tested and the yield and ultimate tensile strength and Charpy impact toughness of the respective samples were then evaluated to establish how these static mechanical properties were influenced by the % planar graphitization. The yield and ultimate tensile strength of the service exposed material did not show a statistically significant correlation with the % planar graphitization. The Charpy impact toughness results did however show a statistically significant negative correlation towards the % planar graphitization. This was clearly evident from the results of the HAZ regions of the service exposed weldments (Samples A-C) which had the highest levels of % planar graphitization and the lowest impact toughness, while the newly welded and post weld heat treated Sample D had no planar graphitization outside the HAZ and the highest impact toughness. This research project not only investigated how planar graphitization affects the static mechanical properties of service exposed pipe material, it also investigated on a microstructural basis, how planar graphitization nucleates and grows. The microstructural investigation showed that the free carbon required for the development of planar graphitization originated from the regions outside the HAZ, which were formed when the pearlite bands were dissolved during the welding of the steam pipe. The heat input from the welding sensitized this region for the development of planar graphitization, probably due to the formation of a “carbon-rich” matrix due to the partial dissolution of the cementite precipitates. All the carbide precipitates in this region consisted of M3C. aluminium-rich precipitates were found inside newly nucleated graphite nodules, indicating its role as a possible heterogeneous nucleation site. Growth of newly formed graphite nodules showed a preference towards high-angle grain boundaries and regions with dislocations for the initial growth stages of the graphite nodules. The microstructure of the region outside the HAZ of the newly introduced seam weld on the service exposed steam pipe material (with graphitization), was also investigated using advanced electron microscopy methods and it yielded no evidence of the development of planar graphitization.
- Full Text:
- Date Issued: 2017
- Authors: Du Preez, Christiaan
- Date: 2017
- Subjects: Graphitization Steam-pipes -- Mechanical properties
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22277 , vital:29933
- Description: The focus of this research project is to establish what effect graphitization has on the static mechanical properties of service exposed ASTM A516 Grade 65 steam pipe material, which operated for prolonged periods above 425 ̊C. The research study was conducted on three graphitized service exposed steam pipe weldment samples and on a newly welded and post weld heat treated sample with graphitized service exposed steam pipe material. Macro samples were removed from each of the samples at two positions and these were evaluated with regard to graphite nodule size, nearest neighbour spacing and % planar graphitization in the parent pipe and HAZ regions on either side of the welds. It was found on all of the service exposed samples that the graphite nodules of the HAZ regions have a smaller median nodule size, smaller median nearest neighbour spacing and increased % planar graphitization in comparison to the parent pipe material. The service expose parent pipe material on either side of the weldments of the respective samples was chemically analyzed. This was done with the focus being on the deoxidizing element content (Si and Al) of the respective parent pipe regions and to what extent these elements influenced the development of planar graphitization in these regions. No correlation could be identified between the level of deoxidizing elements and the levels of % planar graphitization in the parent pipe material. Tensile and Charpy impact samples were removed from the respective service exposed samples parent material on either side of the weld and from the HAZ regions on the side with the highest levels of planar graphitization. These samples were tested and the yield and ultimate tensile strength and Charpy impact toughness of the respective samples were then evaluated to establish how these static mechanical properties were influenced by the % planar graphitization. The yield and ultimate tensile strength of the service exposed material did not show a statistically significant correlation with the % planar graphitization. The Charpy impact toughness results did however show a statistically significant negative correlation towards the % planar graphitization. This was clearly evident from the results of the HAZ regions of the service exposed weldments (Samples A-C) which had the highest levels of % planar graphitization and the lowest impact toughness, while the newly welded and post weld heat treated Sample D had no planar graphitization outside the HAZ and the highest impact toughness. This research project not only investigated how planar graphitization affects the static mechanical properties of service exposed pipe material, it also investigated on a microstructural basis, how planar graphitization nucleates and grows. The microstructural investigation showed that the free carbon required for the development of planar graphitization originated from the regions outside the HAZ, which were formed when the pearlite bands were dissolved during the welding of the steam pipe. The heat input from the welding sensitized this region for the development of planar graphitization, probably due to the formation of a “carbon-rich” matrix due to the partial dissolution of the cementite precipitates. All the carbide precipitates in this region consisted of M3C. aluminium-rich precipitates were found inside newly nucleated graphite nodules, indicating its role as a possible heterogeneous nucleation site. Growth of newly formed graphite nodules showed a preference towards high-angle grain boundaries and regions with dislocations for the initial growth stages of the graphite nodules. The microstructure of the region outside the HAZ of the newly introduced seam weld on the service exposed steam pipe material (with graphitization), was also investigated using advanced electron microscopy methods and it yielded no evidence of the development of planar graphitization.
- Full Text:
- Date Issued: 2017
Effective communication planning for high-performance civil engineering project teams
- Authors: Rossouw, Jeanne Jacques
- Date: 2017
- Subjects: Communication in engineering -- South Africa Communication of technical information , Communication in management Project management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19993 , vital:29020
- Description: In the area of project management, it is well understood that effective communication processes impact positively on project performance. Despite this, project teams still struggle to develop effective communication plans that address their project communication needs. The evidence of this is that many project problems are attributed to poor communication. The literature addresses the needs and shortcomings of group communication and communication planning in general; but there is however, a scarcity of literature describing how to plan for the internal communication needs of high-performance civil engineering teams. With the limited literature available on the topic, this study seeks to validate how effective the current communication planning methods are at Aurecon in meeting the communication needs of its project teams. This qualitative research project is a case study of communication planning within the project teams at Aurecon in Port Elizabeth. A semi-structured interview process was followed, addressing specific questions, without limiting the direction of the interviews. Project team members, working on high performance projects, were asked for their thoughts, feelings and suggestions about existing communication practices and project communication planning. Overall, it was found that the existing communication-planning practices at Aurecon did not have any beneficial effect on how team members communicate. It was concluded that project teams would benefit from improved communication-planning processes that are more inclusive of their specific communication needs. Organisations working on high-performance projects will benefit directly from the research, which challenges these organisations to think more broadly about how they plan for communication at a project level. The research provides practical suggestions for improving the way that teams plan their communication processes; and it does so by focusing on the communication needs of the team members. Recommendations are made to professional bodies, tertiary institutions, project organisations – and most importantly – to project team members themselves. The recommendations to project team members include taking ownership of communication practices, asserting their views, as well as making their needs known.
- Full Text:
- Date Issued: 2017
- Authors: Rossouw, Jeanne Jacques
- Date: 2017
- Subjects: Communication in engineering -- South Africa Communication of technical information , Communication in management Project management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19993 , vital:29020
- Description: In the area of project management, it is well understood that effective communication processes impact positively on project performance. Despite this, project teams still struggle to develop effective communication plans that address their project communication needs. The evidence of this is that many project problems are attributed to poor communication. The literature addresses the needs and shortcomings of group communication and communication planning in general; but there is however, a scarcity of literature describing how to plan for the internal communication needs of high-performance civil engineering teams. With the limited literature available on the topic, this study seeks to validate how effective the current communication planning methods are at Aurecon in meeting the communication needs of its project teams. This qualitative research project is a case study of communication planning within the project teams at Aurecon in Port Elizabeth. A semi-structured interview process was followed, addressing specific questions, without limiting the direction of the interviews. Project team members, working on high performance projects, were asked for their thoughts, feelings and suggestions about existing communication practices and project communication planning. Overall, it was found that the existing communication-planning practices at Aurecon did not have any beneficial effect on how team members communicate. It was concluded that project teams would benefit from improved communication-planning processes that are more inclusive of their specific communication needs. Organisations working on high-performance projects will benefit directly from the research, which challenges these organisations to think more broadly about how they plan for communication at a project level. The research provides practical suggestions for improving the way that teams plan their communication processes; and it does so by focusing on the communication needs of the team members. Recommendations are made to professional bodies, tertiary institutions, project organisations – and most importantly – to project team members themselves. The recommendations to project team members include taking ownership of communication practices, asserting their views, as well as making their needs known.
- Full Text:
- Date Issued: 2017
Evaluating the importance of mangroves as fish nurseries in selected warm temperate South African estuaries
- Authors: Muller, Cuen
- Date: 2017
- Subjects: Mangrove ecology -- South Africa Mangrove fisheries -- South Africa , Estuarine ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12080 , vital:27029
- Description: The value of mangrove habitats as fish nurseries was assessed by comparing communities of early stage and juvenile fishes between estuaries with and without mangroves. Early stage fishes were sampled using boat-based plankton towing while juveniles were sampled by seine netting. Sampling took place at five sites spaced 1 km apart starting near the estuary mouth in four estuaries along the temperate coastline of the Eastern Cape Province of South Africa. Four estuaries were selected based on shared similarities which included catchment area, estuarine area and shared habitats barring the presence of mangroves which occupied the river margins of two systems. Results revealed that early stage and juvenile fish communities (both marine- and estuary-spawned) were similar between systems with and without mangrove habitats. Differences in fish communities among estuaries were rather attributed to axial salinity gradients associated with greater freshwater input, while season and temperature produced significant variances in fish densities with Generalised Additive Models revealing responses of communities to these variables. A common estuarine-dependent fish, Rhabdosargus holubi (Family Sparidae), was further investigated to determine habitat use, residency and dietary patterns in different mangrove habitats. High habitat residency in this species was revealed during a short-term tagging study using Visible Implant Elastomer tags and long-term isotope analysis in juveniles sampled from two contrasting mangrove habitats. A wider feeding niche was observed in an eelgrass-red mangrove connected habitat when compared with more exposed white mangrove areas. Low dependence on mangrove habitats in temperate estuaries is likely due to their tidally dominated inundation and limited refuge potential due to smaller area coverage by mangroves in temperate estuaries. Relatively lower primary productivity in warm temperate mangrove areas, relative to their tropical counterparts, provides no significant feeding advantage or refuge opportunities relative to other available habitats in these estuaries. Warm temperate estuaries, which are both spatially and temporally highly variable, instead host species which are habitat generalists, able to capitalise on these highly dynamic environments.
- Full Text:
- Date Issued: 2017
- Authors: Muller, Cuen
- Date: 2017
- Subjects: Mangrove ecology -- South Africa Mangrove fisheries -- South Africa , Estuarine ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12080 , vital:27029
- Description: The value of mangrove habitats as fish nurseries was assessed by comparing communities of early stage and juvenile fishes between estuaries with and without mangroves. Early stage fishes were sampled using boat-based plankton towing while juveniles were sampled by seine netting. Sampling took place at five sites spaced 1 km apart starting near the estuary mouth in four estuaries along the temperate coastline of the Eastern Cape Province of South Africa. Four estuaries were selected based on shared similarities which included catchment area, estuarine area and shared habitats barring the presence of mangroves which occupied the river margins of two systems. Results revealed that early stage and juvenile fish communities (both marine- and estuary-spawned) were similar between systems with and without mangrove habitats. Differences in fish communities among estuaries were rather attributed to axial salinity gradients associated with greater freshwater input, while season and temperature produced significant variances in fish densities with Generalised Additive Models revealing responses of communities to these variables. A common estuarine-dependent fish, Rhabdosargus holubi (Family Sparidae), was further investigated to determine habitat use, residency and dietary patterns in different mangrove habitats. High habitat residency in this species was revealed during a short-term tagging study using Visible Implant Elastomer tags and long-term isotope analysis in juveniles sampled from two contrasting mangrove habitats. A wider feeding niche was observed in an eelgrass-red mangrove connected habitat when compared with more exposed white mangrove areas. Low dependence on mangrove habitats in temperate estuaries is likely due to their tidally dominated inundation and limited refuge potential due to smaller area coverage by mangroves in temperate estuaries. Relatively lower primary productivity in warm temperate mangrove areas, relative to their tropical counterparts, provides no significant feeding advantage or refuge opportunities relative to other available habitats in these estuaries. Warm temperate estuaries, which are both spatially and temporally highly variable, instead host species which are habitat generalists, able to capitalise on these highly dynamic environments.
- Full Text:
- Date Issued: 2017
Exploring acyl azides chemistry in continuous flow systems
- Authors: Sagandira, Cloudius Ray
- Date: 2017
- Subjects: Organic compounds -- Synthesis Flow chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12065 , vital:27028
- Description: Organic azides are important in the synthesis of many target molecules of great use in fine chemical and pharmaceutical production. The use of this class of compounds is however limited due to their hazardous nature and many safety concerns, as they are highly exothermic. Micro reactors can handle exotherms extremely well, due to the inherent high surface area to volume ratio, unlike the conventional batch process. This dissertation therefore aims to investigate the safe application of micro reactors in acyl azide chemistry.With this in mind, Chapter 1 provides a comprehensive background on organic azides, reaction calorimetric studies, flow chemistry technology (micro reactors) and their theoretical advantages. This chapter also discusses the preparation of organic azides in continuous flow systems and scaling up in continuous flow systems. Chapter 2 illustrates and discusses multivariate optimisation of benzoyl azide synthesis as a model reaction, synthesis of other acyl azides using the model reaction optimised conditions and multistep synthesis of carbamates, amides and amines in continuous flow systems via the Curtius rearrangement of benzoyl azide formed in situ from benzoyl chloride and sodium azide. The chapter also discusses process hazards analysis and evaluation of benzoyl azide synthesis and decomposition using calorimetric studies. It also investigates and discusses the effects of different mixing regimes and channel sizes on scale up. Chapter 3 has comprehensive experimental details for the whole dissertation with Chapter 4 providing the concluding remarks and future work recommendations.
- Full Text:
- Date Issued: 2017
- Authors: Sagandira, Cloudius Ray
- Date: 2017
- Subjects: Organic compounds -- Synthesis Flow chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12065 , vital:27028
- Description: Organic azides are important in the synthesis of many target molecules of great use in fine chemical and pharmaceutical production. The use of this class of compounds is however limited due to their hazardous nature and many safety concerns, as they are highly exothermic. Micro reactors can handle exotherms extremely well, due to the inherent high surface area to volume ratio, unlike the conventional batch process. This dissertation therefore aims to investigate the safe application of micro reactors in acyl azide chemistry.With this in mind, Chapter 1 provides a comprehensive background on organic azides, reaction calorimetric studies, flow chemistry technology (micro reactors) and their theoretical advantages. This chapter also discusses the preparation of organic azides in continuous flow systems and scaling up in continuous flow systems. Chapter 2 illustrates and discusses multivariate optimisation of benzoyl azide synthesis as a model reaction, synthesis of other acyl azides using the model reaction optimised conditions and multistep synthesis of carbamates, amides and amines in continuous flow systems via the Curtius rearrangement of benzoyl azide formed in situ from benzoyl chloride and sodium azide. The chapter also discusses process hazards analysis and evaluation of benzoyl azide synthesis and decomposition using calorimetric studies. It also investigates and discusses the effects of different mixing regimes and channel sizes on scale up. Chapter 3 has comprehensive experimental details for the whole dissertation with Chapter 4 providing the concluding remarks and future work recommendations.
- Full Text:
- Date Issued: 2017
Home ownership in the gap-housing market in South Africa
- Authors: Ludidi, Daniel Dumisa
- Date: 2017
- Subjects: Home ownership -- South Africa Housing -- South Africa , Bond market -- South Africa Real estate investment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/18299 , vital:28616
- Description: The access to adequate housing is a constitutional right, in terms of Section 26 (1) of the Constitution of the Republic of South Africa, Act 108 of 1996. Access to housing in South Africa is still an ideal and not a reality. The increase in housing prices reduces affordability, which creates a barrier to the housing market for South Africans to fully participate. The South African housing market is divided, based on the affordability of households, with a gap within the property market. The gap-housing market is a market, which does not receive a government subsidy; and furthermore, it does not qualify for bond finance by the private financial institutions. The gap-housing market includes households that earn between R3,500 to R15,000 per month for residential properties valued between R116,703 to R483,481. The problem is a lack of supply in the gap-housing market to meet the demand; and this is also affected by the poor performance of the subsidy-housing market. The gap-housing market is not traded adequately, due to a lack of supply caused by stricter lending criteria from the banks. The study was conducted by means of reviewing the related literature and by an empirical study. A survey was conducted using the quantitative approach through a distribution of research questionnaires to different organizations within the judgement sample population. The objective of the study is to review the gap-housing market and to make recommendations. The descriptive survey was conducted among specialists that are participating in the South African housing market. The findings of the study suggest that there is a relationship between incentive and participation, as well as a relationship between participation – with access, supply and trading in the gap-housing market. This study will contribute to the South African housing market body of knowledge – by addressing the problem of a gap within the housing market.
- Full Text:
- Date Issued: 2017
- Authors: Ludidi, Daniel Dumisa
- Date: 2017
- Subjects: Home ownership -- South Africa Housing -- South Africa , Bond market -- South Africa Real estate investment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/18299 , vital:28616
- Description: The access to adequate housing is a constitutional right, in terms of Section 26 (1) of the Constitution of the Republic of South Africa, Act 108 of 1996. Access to housing in South Africa is still an ideal and not a reality. The increase in housing prices reduces affordability, which creates a barrier to the housing market for South Africans to fully participate. The South African housing market is divided, based on the affordability of households, with a gap within the property market. The gap-housing market is a market, which does not receive a government subsidy; and furthermore, it does not qualify for bond finance by the private financial institutions. The gap-housing market includes households that earn between R3,500 to R15,000 per month for residential properties valued between R116,703 to R483,481. The problem is a lack of supply in the gap-housing market to meet the demand; and this is also affected by the poor performance of the subsidy-housing market. The gap-housing market is not traded adequately, due to a lack of supply caused by stricter lending criteria from the banks. The study was conducted by means of reviewing the related literature and by an empirical study. A survey was conducted using the quantitative approach through a distribution of research questionnaires to different organizations within the judgement sample population. The objective of the study is to review the gap-housing market and to make recommendations. The descriptive survey was conducted among specialists that are participating in the South African housing market. The findings of the study suggest that there is a relationship between incentive and participation, as well as a relationship between participation – with access, supply and trading in the gap-housing market. This study will contribute to the South African housing market body of knowledge – by addressing the problem of a gap within the housing market.
- Full Text:
- Date Issued: 2017